For in-flight refuelling operations, one usual method is based on the use of a boom device for interconnecting a tanker aircraft with a receiver aircraft or receptor in flight, which is basically a telescopic or extensible tube attached to the underside of the tanker aircraft by means of an articulation element, that provides fuel passage from the tanker aircraft to the receiver aircraft. At the tanker aircraft, the operator controls visually all steps and procedures for a safe refuelling operation. From the tanker, the operator controls the boom movements and therefore manipulates the boom until it makes a physical connection with the receptacle of the approaching receptor aircraft. Once the refuelling operation is finished in a certain session, the boom is hoisted up to its secured position in the tanker aircraft.
This operation, in particular the approximation operation of the boom relative to the receiver aircraft, is very sensitive and must be effected in a very precise and accurate way because of security reasons.
Typically, and used in the field of robotics, sensing apparatus comprising laser light generators and ultrasound sensors are used for generating signals usable for guiding a robot. This is disclosed, for example, in document U.S. Pat. No. 7,283,892. Ultrasound sensors used in the field of in-flight refuelling operations have the problem of the in-flight air velocity disturbing the sensor measurements, being this problem aggravated by the object being moving.
Another possibility is to use distance measurement by laser interferometry, as it is for example disclosed in documents WO 03/058158, EP 1750086, EP 0469718, EP 0027763 and U.S. Pat. No. 5,828,456. This system is not, however, applied to the field of refuelling.
The present invention comes to solve the above-mentioned drawbacks.